Coating apparatus



Aug. 25, 1964 Original Filed April 18, 1960 H. :HAYEK ETAL COATINGAPPARATUS 2 Sheets-Sheet 1 INVENTORS HERMANN HAYEK JOSEF ZEMANN JOHANNESEISENWIENER H. HAYEK ETAL COATING APPARATUS Aug. 25, 1964 INVENTORSHERMANN HAYEK JOSEF ZEMANN JOHANNES EISE IENER United States Patent 2Claims. c1. 118-64) The present invention relates to apparatus for usingwater-soluble and water-dispersible coating agents as well as ofcombinations of these two, in fact to all waterdiiutable coating agents,for coating articles in the coater.

The flow-coater process is known in the art per so (see, for example,Industrie-Lackier-Betrieb, 26th Year, pages 320 ff., 1958). However,water-dilutable coating agents have previously not been used in acoating process for various reasons. For example, previously, socalledcurtains and tears were formed and the coated objects had such unevensurfaces that they were not very well suitable for further use,especially for applying lacquer covers thereto. Other problemsencountered were foam formation, poor stability of the water-dilutedcoating agents over long periods of operation; tendency toward craterformation on the lacquered objects; the uncertainty whether the watervapor produced in the drain tunnel of the flow-coater would behave asfavorably as the solvent atmosphere which is developed in the draintunnel upon evaporation of the organic solvents in conventionallacquers, etc.

An object of our invention is therefore to provide an apparatus forapplying a uniform coat of a water dilutable coating agent to an articlein a coater, wherein the coat is free from surface defects.

Further objects of our invention are to overcome the problems enumeratedabove in the use of water dilutable coatings in a coater.

These and other objects of our invention will become apparent as thedescription thereof proceeds.

This application is a division of our co-pending application Serial No.23,019, filed April 18, 1960, Process for Coating Objects in aFlow-Coater, in which the process is more fully described.

Referring to the drawings which illustrate embodiments for carrying outour invention,

FIGURE 1 illustrates a coating apparatus in elevation cross-section,showing spraying and drying sections.

FIGURES 2, 3 and 4 illustrate the coater in end elevation and showvariations of a means to prevent marn'ng of the coated article in thedrying chamber by condensed droplets of the sprayed coating mixture.

In the drawings, FIG. 1 is a schematic representation of the coater. 1is a container for the coating agent, 2 is the container for theadditive composition which may be water or water and solvent and 3 isthe automatically controlled valve, for example a controlled viscositymeasuring device which is not shown, by means of which the additivecomposition for maintaining uniform viscosity as discussed above, isadded from container 2 to the coating composition in container 1 duringthe entire operation. 4 is a spray chamber with nozzles 7, in which theobject 5 to be coated is introduced into the spray chamber by means of atransport device 9, preferably a chain attached to a roller 8 or othersliding device, which glides over a rail 6. The objects 5 are treatedwith the coating composition and are 3,146,128 Patented Aug. 25, 1964transported into the tunnel-like chamber 10 (called draintunnel) in thedirection of arrow a. Beyond the drain tunnel a drying tunnel 10a isprovided. In the drain chamber the excess coating composition drips fromthe treated objects, whereas the coating layer adhering to the objectsdries. The drying can be regulated by drawing air through the draintunnel. The excess of coating composition introduced into the spraychamber as well as the coating composition dripping from the objects inchamber 10 falls onto drain surfaces 23 and runs back into container 1,so that the coating composition is constantly cycled. The coatingcomposition is cycled from tank 1 to nozzles 7 by conduit means notshown. The apparatus of FIG. 1 is mainly diagrammatic to illustrate thevarious necessary elements and their functions. It will be understoodthat the solvent composition tank could be located differently and thatother modifications are possible.

We have found that when working in accordance with the coating processof our co-pending application S.N. 23,019, large quantities of water andsolvent which are present in the coating composition continuouslyevaporate in the drain tunnel. We have now found that it is verydetrimental that the water or solvent vapor condenses on the walls ofthe drain tunnel because the condensate which settles on the ceiling ofthe drain tunnel, drips down on the passing objects which have beencoated with the coating composition and have not yet dried causingdamage to the coating composition surface film. These objections can beovercome by the use of apparatus of the type illustrated in FIGS. 2, 3and 4.

FIG. 2 shows a drain tunnel with a heatable ceiling; FIG. 3 shows astationary arrangement of cover draining means in the interior of thetunnel; and FIG. 4 shows an arrangement of cover draining means attachedto the transport means for the objects which have been coated with acoating composition film.

In FIG. 2, 21 represents the walls, 22 the ceiling and 23 the floor ofthe drain tunnel 24 in cross section. 26 is the transport rail, 28 awheel of the transport means 29 to which the object 25 to be coated isattached to pass it through the coater. Ceiling 22 in FIG. 2 is providedwith cover means 22a heating coils 210 to make it heatable.

In FIG. 3 the drainage means are in the form of flat pieces of sheetiron 211a and 211b, sheet 211a being attached to the transport rail 26and the other sheet 211b being fastened to ceiling 22 of the draintunnel 24. In FIG. 4 a protective device 212a and 21% is provided on thetransport means 29 which may be shaped in such a way as to be inclinedtoward all sides, if necessary, and may assume various forms when viewedfrom the top. The width of the protective pieces of sheet iron must besuch that they provide adequate protection of the objects againstdripping of condensate from the ceiling of the drain tunnel or from anyparts of the apparatus mounted immediately below the ceiling. Theinvention, however, is not limited to the embodiments shown in thedrawing.

While we have set forth certain specific embodiments and preferred modesof practice of our invention, it will be understood that this is solelyto illustrate the invention and enable persons skilled in the art tobetter understand and practice the invention. Various changes andmodifications may be made in the invention without departing from thespirit of the disclosure and the scope of the appended claims.

We claim:

1. In a coating apparatus for coating objects with water dilutablecoating agents comprising spraying and drying sections and means forconveying objects through said sections, cover means above saidconveying means extending the length of said drying chamber to preventdroplets of sprayed coating agent condensing above the coated objectsfrom falling on the freshly coated surface of said object in said dryingchamber.

2. In a coating apparatus for coating objects with Water dilutablecoating agents comprising spraying and drying sections, track meansalong the ceiling of said sections, movable means to travel along saidtrack means, and cover means attached to said movable means above saidobjects to prevent droplets of sprayed coating agent condensed on theceiling of said drying section from falling on the freshly coatedsurface of said object in said drying chamber.

References Cited in the file of this patent UNITED STATES PATENTS HarrisAug. 2, Grupe Mar. 19, Adams May 15, Page et a1. Dec. 1, Uhlig et a1.Feb. 22, Graf Aug. 28, Ransburg Nov. 5, Norris Aug. 19, Jones May 19,Wallis Nov. 14, Norman et al. Oct. 3, Glaus Dec. 4,

FOREIGN PATENTS Australia Ian. 26,

1. IN A COATING APPARATUS FOR COATING OBJECTS WITH WATER DILUTABLECOATING AGENTS COMPRISING SPRAYING AND DRYING SECTIONS AND MEANS FORCONVEYING OBJECTS THROUGH SAID SECTIONS, COVER MEANS ABOVE SAIDCONVEYING MEANS EXTENDING THE LENGTH OF SAID DRYING CHAMBER TO PREVENTDROPLETS OF SPRAYED COATING AGENT CONDENSING ABOVE THE COATED OBJECTSFROM FALLING ON THE FRESHLY COATED SURFACE OF SAID OBJECT IN SAID DRYINGCHAMBER.